Acoustic Treatment Basics

Tame those wild frequencies

For those of us who have home studio setups, or a recording rig at their band room, the issue of acoustic treatment is one which perhaps goes under the radar slightly. Sure, we’ve all seen those pictures of high end studios with obscurely shaped pieces of foam on the walls and muttered something about “improved acoustics”, but how and why does acoustically treating your recording space actually benefit your recordings? With the help of the excellent infographic below, courtesy of Resonics, we’ve got some answers for you.

Thankfully, the science behind it is actually pretty straightforward. Sound, as you probably know, travels in waves which can ‘bounce’ off certain surfaces. As an extreme example, imagine shouting at the top of your voice in the shower. Now imagine shouting at the same volume when stood on top of a mountain. It’s going to sound different, right? That’s because when you’re in the shower, the sound waves are going to bounce back and forth between the walls. This is called primary reflections, and is the most obvious way to cloud the sound in your room.

As another example, have you ever recorded something and mixed it so it sounds amazing in your studio, only to listen back to it in the car or through your headphones and hear it sounds either too muddy or too thin. This is more than likely due to the fact that you’ve mixed it according to the room, not according to the sound as it actually is. Every room has its own quirks and foibles when it comes to sound distribution and, while there is no right or wrong room as such, there are certain principles which will help immensely in producing a more balanced mix.

Bass is perhaps the trickiest of the frequencies to get right. Low end frequencies have a nasty habit of bunching up in the corners of rooms which can cause the producer to over-compensate in the mix leaving everything muddy and flat. Even if the type of music you’re creating is specifically bass focused, there’s much more to it than simply boosting those frequencies in your EQ. Consider the impact the room is having on your recording. The infographic has some excellent tips on placement of dedicated acoustic foam traps which will go some way to soaking up those errant bass frequencies and, as ever, test your mixes on more than one set of speakers before releasing it into the wild.

Another tricky element to tame can be natural reverberation, particularly if you record in a large untreated space. Reverb is the sound caused by sound waves bouncing back off walls or other objects and reaching the microphone or recording device after they have been played. In many instances, a degree of reverb is highly desirable and can give an otherwise sterile recording a bit of life. Again, there are no rules here, but if unwanted reverb is causing your mixes to sound slightly washed out then you might consider acoustically treating certain areas of the room, or confining the space in which the sound is reverberating. Vocals are often a good example of this, which is why you’ll often see vocal microphones hidden behind special filters or portable booths like the SE Electronics Reflexion Filter X Portable Vocal Booth. The thing with reverb is that it’s easy to ‘dial in’ a nice dash of it onto your dry recorded signal, but you can’t really remove it once it’s there naturally. By using a filter you at least have control over the sound and can make it how you want it, not how your room dictates. This is also true of recording guitar amplifiers and speaker cabinets; constructing makeshift booths out of chairs, duvets, pillows or sheets can produce a much more focused sound which is far easier to control at the mixing stage.

It goes without saying that your monitor speakers play a huge part in what you can hear and your subsequent ability to mix efficiently. Studio monitors are usually offer a flat-frequency response, which means they don’t accentuate any particular frequency. This differs from your Hi-Fi or car speakers, which tend to boost low and higher frequencies and attenuate (cut) the mid-range. Flat frequency speakers mean the sound isn’t treated in any way before it hits your ears, which in turn means you can mix your tunes knowing that any changes you make to EQ are accurate and not being subtly changed by the speakers. Also important is speaker placement within the studio. Imagine an equilateral triangle, with you at one point and the two speakers (at head height) at the other two points, directed at your head. An ideal setup would have the desk and speakers a short distance from the wall, i.e. not right up against it, with the speakers on stands like these. To go one better, rest the speakers themselves on isolation pads like these, which reduce the amount of distortion and vibration caused as the sound leaves the speakers.

If you’re truly serious about acoustic treatment, you might want to go full-on Bob the Builder and begin analysing the room from a construction perspective. It figures that acoustic treatment is as much about what sounds enter the room than it is about what sounds are produced within the room. You might have the perfect setup within your four walls, but people coming in and out of other rooms, cars going past, next door watching Neighbours re-runs at two in the morning; all these things are largely out of your control but could impact on what you’re trying to do in your studio. Soundproofing, the art of locking a sound into one place, is where acoustic treatment goes ‘next level’, and the possibilities here are significant.

If you’re of a mind to begin pulling down walls and ripping out floorboards – and you have the skills, finance and permission to do so – then you might consider examining the types of insulation used in the walls, the thickness of the doors and windows etc. There’s plenty of advice from Resonics in the infographic so check that out for ideas.

We’ll end this with a final point that doesn’t involve buying new gear or ripping out interior walls. It’s a simple thing that anyone can be mindful of, and that’s listening fatigue. You can have the most optimally treated, silent, soundproof room in the world but if you don’t look after the tools with which you listen to your music – your ears – then no amount of acoustic foam is going to help you. But, by listening to the advice above, and taking care of your ears by giving them a proper rest every few hours, we’re certain your mixes will sound more consistent, more balanced and more professional in no time at all.